How many molecules does 85.0 g hcl contain?

To find the number of molecules in 85.0 g of HCl, first calculate the number of moles using its molar mass (approximately 36.46 g/mol). The number of moles is 85.0 g / 36.46 g/mol ≈ 2.33 moles. Then, multiply the number of moles by Avogadro's number (approximately (6.022 \times 10^{23}) molecules/mol): 2.33 moles × (6.022 \times 10^{23}) molecules/mol ≈ (1.40 \times 10^{24}) molecules of HCl.